Flow dividers



` A. KEEL FLOW DIVIDERS Filed Feb. l2, 1965 June 2, 1964l United StatesPatent O 3,135,283 FLOW DIVIDERS Adolf Keel, 164 California Ave.,Highland Park, Mich. Filed Feb. 12, 1963, Ser. No. 258,044 3 Claims.(Cl. 137-118) The invention relates to fluid power transmission, andapplies to the actuation of two fluid motors from a single power source.

More particularly, the invention pertains to such applications where two:duid motors must be driven at closely proportional speeds over a rangeof speeds and under conditions involving unequal loads` on the twomotors. It is intended for such systems in which a variable quantity offluid is delivered at the power source, and in Y which the operatingpressure depends upon the pressure of the more heavily loaded of the twomotors. These conditions require a typeY of flow divider control whichwill maintain a predetermined division of fluid ilowing to the motorsregardless of varying resistances in one or the other of the two motors.

In is the object of this invention to attain an accurately proportionatedivision of iluid from this power source to the fluid motors over aconsiderable range of speeds, in a pulsation free llow, independent ofload variations in either of the two fluid motors, and at operatingpressures not substantially in excess of the uid motor operatingpressures. The principle and the advantages of the present invention aredescribed in greater detail in the following specification in which FIG.1 is a cross sectional view of the ilow divider, and

FIG. 2 is a plan view of the inlet side of the same.

Referring now to FIG. 1, the body 11 is provided with inlet port 12 andoutlet ports 13 and 14. Inlet port 12 leads to the central thru bore 15which at the inlet end is fitted with bushing 16 and at the opposite endwith bushing 17. Bushings 16 and 17 are axially held in position by thesnap ring 18 and the sealing plug 19 respectively. A pin and groovelock, not shown in the drawing, in the head of bushing 16 iixes itsangular position. Sealing plug 19 is held against the head of bushing 17by the cover 20. Bushings 16 and 17 serve as support for the valve spool21 whose diameter has one half the cross sectional area of the bore 15.Valve spool 21 is provided with a shoulder 22 which is somewhat smallerin diameter than bore 15. Shoulder 22 serves as a stop for spool 21 whenthe latter is urged against bushing 16 by the spring 23, and it alsoserves as a shoulder for piston 24 which is slidably fitted in bore 15and over spool 21 in the space formed between bushings 16 and 17.Bushing 16 has two radial orifices 25 and 26 leading to hydrostats 27and 28 respectively. The size of these orifices is governed by the edgeat the end of spool 21, and may be anything between the closed positionshown and a full opening. Hydrostats 27 and 28 establish the connectionbetween orifices 25 and 26, and the outlet ports 13 and 14 by Way ofannuli 29 and 30 respectively. Each of the hydrostats embodies a springbiased piston fitted slidably to a chamber adjacent to and in connectionwith orillce 25 or 26. The outer ends of the hydrostat pistons are incommunication with the inlet port by way of passages 31, 32, 33, and 34.Passages 32 and 34 also are in undirectional communication with theannuli 29 and 30 thru check valves 35 and 36 which permit ow in thedirection of the inlet port only. For a condition not involving any backpressure in either of the outlet ports, the operation of the flowdivider proceeds in the following marmer:

Fluid entering the inlet port lirst iiows to the outer pass thruorifices 25 and 26 into the hydrostats.

Patented June 2.., 1964 ICC f2 5 and 26, and their respective outletports. Further admissionof iluid causes a rise in pressure until thevalue set by spring 23 is reached, at which point spool 21 is displacedaxially to the extent that some fluid is allowed t0 As this is takingplace, the hydrostat pistons will begin to move outwardly as soon aslluid pressure on the spring side of the pistons reaches a value equalto the inlet pressure minus the pressure equivalent of their springs.The outward movement of the hydrostat pistons continues to the jointwhere just enough fluid is allowed to escape into the annuli and theoutlet ports thru` the metering notches 37 that this pressuredifferential between the inlet pressure and the pressure on the springside of the hydrostat pistons in maintained. If we now assume, forinstance, the pressure equivalent of spring 23 to be 50 p.s.i., and thatof the hydrostat springs to be 30 p.s.i., it follows that for any givenliow within the capacity of the unit the fluid pressure inside thehydrostat chamber will `25 and 26 are of the same size and shape, itbecomes evident that the flow thru the two orilices is equal because of'a constant and equal pressure drop maintained across the orifices.

Considering now a condition where a resistance to llow exists in outlet13 which requires aipressure of 200 p.s.i to overcome it, and noresistance in outlet 14, we assume, as in the preceding case, that thepressure equivalent of spring 23 is 50 p.s.i. at the point of opening oforiices 25 and 26, -and that the hydrostat springs will amount to 30p.s.i. at the cracking point of the hydrostats. Fluid entering the unitwill again lirst close the hydrostats, and then, as the pressure risesto 50 p.s.i., begin to open orifices 25 and 26. `As soon as the pressurein the hydrostat chambers reaches 2O p.s.i. (S0-30), the hydrostats tendto open. Any llow into port 13, however, will immediately begin to buildup pressure in that port, since a pressure of 200 p.s.i. must be reachedbefore any appreciable flow can take place. But any pressure build up inport 13 is transmitted at once to piston 24 thru passage 40, thusassisting spring 23, and helping to maintain a pressure dilference of 50p.s.i. between port 13 and the inlet port. Consequently, flow acrossorifice 25 can take place only after the pressure in the inlet port hasclimbed to 250 p.s.i. Fluid going to outlet 13 thus is at a pressure of250 p.s.i. in the inlet port, 220 p.s.i. in the hydrostat chamber, and200 p.s.i. in port 13. On the way to port 14, lluid pressure drops from250 p.s.i. to 220 p.s.i. from inlet to hydrostat chamber, and from thereto 0 p.s.i. in port 14. In spite of the pressure difference existingbetween the two outlet ports, the flow over the two orifices remainsequal because of the constant and equal pressure drop maintained.

If now a resistance developes in outlet 14, the pressure in this port istransmitted simultaneously to the spring end of spool 21 thru passage39, and to the side of piston 24 contacting shoulder 22 thru passage 38.Since piston 24 and spool 21 are equal in cross sectional area, theforces exerted on spool 21 by this pressure rise are equal and opposite,and cancel each other out as long as the pressure in port 14 is belowthat of port 13. As soon as iluid pressure in port 14 beings to exceedthat of port 13, piston 24 is pushed against bushing 17, and thepressure in port 14 begins to act effectively against the spring end ofspool 21. If now the pressure in port 14 again drops below that of port13, pressure in the latter port forces piston 14 away from bushing 17and against shoulder 22, thus returning the pressure control to port 13.The separating of piston 24 from shoulder 22 or from the upper end ofbushing 17 during the change of the higher outlet pressure from one portto the other re- Vquires that the contact surfaces on both ends ofpiston Z4 be so constructed as to permit ready access of the Huid mediumthereto, a detail which is not shown in the drawm Y Y g1`hus it may beseen that the present invention permits an accurate division of avariable fluid ow to two outlets at an inlet pressure determined by andnot substantially greater than the higher of the two outlet pressures.An unequal but proportionate division of iiow mayV be obtained by theincorporation of suitable oriiices and by employing unequal but constantpressure drops across the metering orices.

Check valves 35 and 36 between the annuli of the hydrostats and passages32 and 34 respectively provide for a return flow from the outlet portsto the inlet port.

What I claim is:

1. A valve structure comprising, in combination, a

body, aninlet port and two outlet ports on said body, a

movable spoolY governing two variable orifices in said body between saidinlet and outlet ports, fluid pressure responsive means for maintaininga constant pressure drop across each one of said two oriiices, springmeans for biasing said spool to keep the said orifices closed againstthe pressure of incoming iiuid, said spring means beingof greatermagnitude than the said pressure drop across either of the oriiices, anduid pressure responsive means acting upon said movable spool so as toadd to the said spring means any pressure increase in the one of the twooutletV ports having the higher fluid pressure of the two.

2. In a ow dividing valve, the combination of a body having one inletport and two outlet ports, a movable spool governing two variableorifices in said body between said inlet and outlet ports, fluidpressure responsive means for maintaining a constant pressure dropacross each one of said two orifices, spring means for biasing saidspool to reduce the size of the said two orifices against the pressureof incoming iiuid, said spring means being of greater magnitude than thesaid pressure drops across either of the orifices, fluid pressureresponsive means acting upon said movable spool so as to add tothe saidspring means any pressure increase occurring in the one of the twooutlet ports having the higher fluid pressure of the two ports,

and two check Valves, one each being interposed between an outlet portand the inlet port so as to permit a direct return tiow from the outletports to the inlet port.

3. In a flow dividingvalve, the combination of a body having one inletport and two outlet ports, a chamber formed in said body adjacent to theinlet port, means in said chamber forming two bores of minor diameterand of like size, one at each end, and a major diameter bore between thetwo bores of minor diameter, said major diameter bore having twice thecross sectional area of one of the minor diameter bores, said chamberbeing open at one end to the inlet port of the body and being closed atthe opposite end, two openings in the minor diameter bore of the chambernear the inlet port, each of said openings leading to control Valvemeans for maintaining a constant pressure drop across each of saidopenings, a spool slidably iitted to the minor diameter bores of saidchamber, said spool having such axial freedom of movement as to becapable of opening and closing the said openings in the minor diameterbore near the inlet port, means forming a shoulder on said spoolsomewhat smaller than the major diameter bore of said chamber and actingas an aXial stop for the spool in the direction of the inlet port,spring means disposed in the closed end of said chamber to bias saidspool in the direction toward the `inlet port, a movable sleevetype'pistonrfitted slidably to the major diameter bore of the saidchamber and fitted slidably over the said spool on the side of saidshoulder away from the inlet port, a fluid passage from one of theoutlet ports to the major diameter bore of said charnber entering on theside of said piston away from the inlet port, a fluid passage from theother of the outlet ports to the major diameter bore of said chamberentering on the side of the piston toward'the inlet port, and asecond'uid passage from this latter outlet port to the closed end of theminor diameter bore of said chamber.

References Cited in the file of this patent UNITED STATESPATENTS2,157,707 Keel May 9, 1939 2,365,095 Miller et al Dec. 12, 19442,750,953 Helsey et al June 19, 1956

1. A VALVE STRUCTURE COMPRISING, IN COMBINATION, A BODY, AN INLET PORTAND TWO OUTLET PORTS ON SAID BODY, A MOVABLE SPOOL GOVERNING TWOVARIABLE ORIFICES IN SAID BODY BETWEEN SAID INLET AND OUTLET PORTS,FLUID PRESSURE RESPONSIVE MEANS FOR MAINTAINING A CONSTANT PRESSURE DROPACROSS EACH ONE OF SAID TWO ORIFICES, SPRING MEANS FOR BIASING SAIDSPOOL TO KEEP THE SAID ORIFICES CLOSED AGAINST THE PRESSURE OF INCOMINGFLUID, SAID SPRING MEANS BEING OF GREATER MAGNITUDE THAN THE SAIDPRESSURE DROP ACROSS EITHER OF THE ORIFICES, AND FLUID PRESSURERESPONSIVE MEANS ACTING UPON SAID MOVABLE SPOOL SO AS TO ADD TO THE SAIDSPRING MEANS ANY PRESSURE INCREASE IN THE ONE OF THE TWO OUTLET PORTSHAVING THE HIGHER FLUID PRESSURE OF THE TWO.